This apparatus comprises generally at least one arresting arm forming a "blade," pivotally mounted with respect to the ski by means of a hinge. This arm is normally found in an active braking position in which it projects under the bottom of the ski. A pedal articulated to the ski, connected to the arresting arm, extends above the upper surface of the ski and acts in opposition to an elastic member. When pressed towards this surface by the shoe, this pedal moves the arresting arm to an inactive position. In active position of the ski brake, the blade or the arresting arms penetrate more or less into the snow, the ski immobilizing itself on the slope and the skier can easily recover it. The ski therefore does not risk descending the slope and injuring the skier located down the slope or becoming lost.
In order for the ski brake to be effective, it is necessary that the elastic member which activates the blade and makes it pass from its inactive position to its active position, retains a certain state of compression when the blade is in active position. In fact, if this elastic member was totally relaxed, the blade would be pushed back by obstacles and the ski would slide by itself on the slope as if there had not been a blade.
Another solution consists of locking the blade in active position of brakage. This latter solution presents, however, certain disadvantages because, in order for the lockage to take place, it is necessary that the blade attain the locking position corresponding to the maximum travel and furthermore, in active position of brakage, due to the fact that the blade is locked, there is no longer any elastic support of this blade, which increases the risk of breakage of the brake.
The first solution, consisting of utilizing an elastic member strongly stressed in active position, is therefore preferable but is a delicate application as the tension remains very high in inactive position, which leads to, at the time of "step-in" of the boot, forces clearly greater than those which the skier can normally exert. Additionally, and in particular the pedal exerts in the mounted position a force tending to raise the sole and this pressure can disturb the operation of the safety device. Furthermore, preliminary tension of the spring is further elevated and in contrast the force to be exerted by the skier at the time of step-in is increased with increase of the travel of the blade. Finally, certain useful energization apparatus only permits a limited travel.